This invention is directed to refrigerated product display cabinets or cases which are used in self-service markets, stores and other establishments in which products are illuminated, viewed, selected and purchased.
The invention is particularly directed to a refrigerated display case or cabinet which is operated below external ambient temperature. Typically, such display cases include one or more insulated glass doors through which products, such as ice cream, yogurt, or the like, on shelves in an interior refrigerated compartment can be viewed, selected and removed. The display doors can be mounted for sliding movement or pivotal movement and each door typically closes a large opening defined by a door frame. More often than not, a typical door frame includes upper and lower horizontal frame members, opposite vertical end members, and therebetween one or more vertical mullions. Illumination is generally provided by florescent tubes conventionally mounted vertically along the vertical mullions and/or end frame members or horizontally along the horizontal top frame member. Conventional electrical ballasts are associated with the florescent tubes, and heretofore such ballasts have been mounted in a number of different ways with respect to the upper horizontal frame member and vertical mullions of a typical conventional refrigerated display case.
As one typical example of ballast mounting, a ballast which includes oppositely directed mounting flanges and mounting holes or slots is fastened against an inside or a cold side wall of a vertical mullion or an upper horizontal frame member, and a separate cover then covers the ballast and is separately secured to the vertical mullion or upper horizontal frame member. When a ballast is so attached to an upper horizontal frame member, servicing from the exterior of the refrigerated display case is oft times difficult and time-consuming because a service person must open the display door associated with a door opening, reach in and above, and manipulate fasteners to remove the cover and ballast, disconnect the ballast from wiring, reconnect the new ballast and reinstall and recover the same. A solution to the latter problem is proposed in U.S. Pat. No. 5,720,540 granted on Feb. 24, 1998 to Charles E. Crown et al. which initially describes the conventional use of a ballast can into which a ballast is housed and which can be accessed through an opening of the ballast can typically closed by a door. As the patentees explain, when prior art ballast cans are mounted on the inside rearward facing wall of a frame, the access to the ballast can opening is in a direction from the rear of the display case resulting in the same problem as that presented when the ballast is directly attached to a horizontal upper frame member or a vertical mullion. The latter patent provides a ballast door which opens downwardly, as one example, and the ballast can be carried by the ballast door to effect better access for repair/replacement purposes.
Typically, ballasts can also be housed in vertical mullions, as disclosed in U.S. Pat. No. 5,645,330 granted on Jul. 8, 1997 in the name of Paul J. Artwohl et al. This patent acknowledges the utilization of vertical mullions to mount and house florescent tube ballast but conventional mounting systems therefor are said to make it difficult and time-consuming to gain access to the ballast for service and replacement. The patentees propose forming a side access opening in a side wall of a vertical mullion and removably connecting a conventional ballast to a ballast drawer which can be slid into and out of the vertical mullion through the side access opening. The ballast drawer includes a support plate having a pair of lanced tabs which rententatively engage complementary tongues on the ballast. A pair of fasteners secure the ballast drawer to the vertical mullion which is then covered by a cover plate. Though providing a solution to an acknowledged problem, the ballast drawer concept presents additional problems, most notable among which are the cost to manufacture the ballast drawer, including blanking and forming operations, particularly with respect to forming the lanced tabs and assembling the ballast relative thereto. In addition, the ballast drawer can only be inserted into the side wall access opening of the vertical mullion in one relative position between the two which can increase, not decrease, disassembly, servicing/replacement and reassembly.